Named after the Greek word "acanthi", meaning “thorn,” in reference to the mineral’s common crystal habit. Acanthite is a common mineral that occurs in medium- to low-temperature hydrothermal sulfide veins and in secondary enrichment zones. It can be found in association with silver, pyrargyrite, proustite, polybasite, stephanite, aguilarite, galena, chalcopyrite, sphalerite, calcite, and quartz. A widespread mineral, but fine crystals can be found in localities in the Czech Republic, Germany, Mexico, the United States, Canada, and Chile. Found in silver rich deposits as lead grey to black tarnished, soft, metallic pseudocubic crystals or elongatic prismatic crystals with rounded corners commonly associated with Silver. Sectile and easily cut by a knife.

Named to honor French mineralogist Gilbert-Joseph Adam who supplied the first samples. Adamite is an uncommon secondary mineral that can be found in oxidized zinc and arsenic bearing hydrothermal deposits. Well studied material and fine specimens come from localities in Chile, Mexico, the United States, France, Germany, England, Greece, Namibia, and Australia. Adamite can fluoresce and phosphoresce a lemon-yellow under long- and short-wave ultraviolet light. Often as formless glassy crystalline crusts in zinc rich load deposits with slight yellow tinge. Typically translucent, vitreous or glassy yellow to yellowish green fanlike crystals (Mina Ojuela). Colored by impurities, especially Copper, when green or Manganese when purple.

Named for Professor Frank Dawson Adams of McGill University in Montreal, Canada, who was a geologist and petrologist who studied the Monteregian Hills, one of which is Mont Saint-Hilaire where the mineral finds its type locality at the Poudrette quarry. There are only two other localities for Adamisite-Y at Hundholmen in Nordland, Norway, and at the Shomiokitovoe pegmatite in the Lovozero massif on the Kola Peninsula in Russia. Adamsite-Y should not be confused by name with Adamsite, which is a variety of muscovite. Snow white fibrous crystals. A rare late-stage, low-temperature hydrothermal mineral in an alkalic pegmatite dike associated with an intrusive alkalic gabbro-syenite complex.

Named for Norse-Scandinavian sea-god Aegir, as the mineral was first described from Norway where the mineral’s two co-type localities lie at Rundemyr, and Laven. Aegirine is relatively common and widespread, and can be found in additional localities in Sweden, Spain, Russia, Greenland, Tanzania, Malawi, the United States, and Canada, among several others. It occurs commonly in alkalic igneous rocks, carbonatites, pegmatites, regionally metamorphosed schist, gneiss, iron formations, blueschist facies rocks, granulites as a result of sodium metasomatism, and as an authigenic mineral in shale and marl. Dark green acicular micro crystals in low silica igneaous rocks. Also as prismatic deep green crystals up to 5cm or more or radial groups embedded in matrix.

Named for the Greek word ainigma, meaning “a riddle” and also the root of the common word enigma, in reference to the mineral’s, at the time, unknown or uncertain chemical composition. Aenigmatite is an uncommon mineral that is often a primary constituent of sodium-bearing alkalic volcanic rocks, pegmatites, and other igneous rocks that are silica-poor. Localities for Aenigmatite include in Greenland, Russia, Norway, Italy, the United States, Australia, and New Zealand, among many others.